1 September 2014

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Health Report 29 min 2 speakers 8 chapters transcribed 4 days ago

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Transcript generated automatically by AI and may contain errors.

What question should I ask my GP before a colonoscopy referral?

Dr. Norman Swan 0:00

Today on the Health Report, the question you absolutely must ask your GP about the specialist she's referring you to for your colonoscopy. It will get them both on their toes and give you a more reliable result. And cutting out the bull when it comes to stem cells. Stem cells have become big business with orthopedic surgeons offering cartilage stem cells for knee arthritis, patients flying to Germany for all sorts of supposed Stem cell treatments, and researchers touting cures for Alzheimer's disease and even offering to build new hearts and livers. Well, the person who co-discovered human blood stem cells reckons that a lot of this is either a con or going nowhere, and that governments and regulators need to get a lot tougher on purported stem cell treatments.

Dr. Norman Swan 0:45

Irv Weissman also thinks the public sector can get stem cells to the clinic faster and easier. and cheaper than the pharmaceutical industry, and that there is good news. Professor Weissman is director of the Institute for Stem Cell Biology and Regenerative Medicine at Stanford University in California. He's in Australia at the moment as the guest of the National Stem Cell Foundation, a not for profit organization.

Irv Weissman 1:06

In born people, stem cells are the cells that regenerate your tissues. They do so by self renewing. That means when they divide one cell to give rise to two, on average one of the two is still a stem cell. Of the other cells that are derived from it, every time they divide they take a step toward becoming the tissue cell. So a blood forming stem cell self renews, keeps the same number forever by self-renewing one of two, but then the daughter cell that doesn't self-renew goes through stages of development of commitment to make each of the different blood cells and probably So, you know, I think that's a

Dr. Norman Swan 1:53

a sense they keep some in the bank the bank deposit remains the same and then the other daughter goes off to become a T cell or with non blood stem cells, bone, brain

Irv Weissman 2:05

Or your bowel. That's right. And every stem cell can only make the tissue where you find it. So brain stem cells make brain only, blood forming stem cells make blood only, bowel stem cells make the intestinal cells only.

Dr. Norman Swan 2:21

And this is where it gets a bit confusing because there are stem cells, but embryonic stem cells from the embryo when there's only a few cells in the embryo which can become anything you like, in theory.

Irv Weissman 2:32

That's right. So very early after the egg is fertilized and before the fertilized egg implants in the uterus to start embryogenesis, it divides itself into two kinds of cells, those that will attach to the universe uterus so that it can make a placenta, and just about twenty cells that don't have any decisions yet but will make decisions once the preemption. the embryo implants in the uterus.

Dr. Norman Swan 3:00

And there's been this debate about what you know, this is the what's so called pluripotent stem cells, whether in fact you can make the stem cells which are already predestined to become bowel or brain, whether you can turn them back into becoming pluripotent in the sense of the embryonic stem cells that you've just described.

Irv Weissman 3:18

Yes, it doesn't happen naturally. You have to induce them with genes that you insert or the gene products you insert into the cells to go all the way back to the stage of being, those inner cells in the preembryo. The embryonic stem cells are only stem cells because you can grow them in a petri dish or a plate or a test tube. They don't know normally self renewed so we don't have any remnant of pluripotent cells left in our body after we're born, nor do we have any of the intermediate tissues.

How do adult stem cells differ from embryonic pluripotent stem cells?

Irv Weissman 3:52

We just have the organs and tissues that adult stem cells regenerate. How

Dr. Norman Swan 3:58

reliable is the science of turning adult stem cells back into something which can become anything?

Irv Weissman 4:06

It's pretty good, but because you need in most cases to genetically modify them, the genes you put in can insert into the chromosomes, and they don't necessarily turn on and turn off at the right time. And where they insert they can disrupt a gene or activate a gene.